1. Field
One or more example embodiments relate to an apparatus and method for controlling a speed of a satellite antenna, and more particularly, to a method of optimizing a driving speed of an antenna provided in a low earth orbit satellite.
2. Description of Related Art
Numerous satellites may use an antenna having a specific effective beam width and directivity to transmit image data to a terrestrial destination. Due to a limited beam width of an antenna, the antenna may need to be oriented to a ground station to transmit image data. In a case of a multi-purpose satellite, a biaxial gimbal-type structure may be used to orient an antenna to a specific direction An orientation of the antenna may be represented by angles in two axes, for example, an angle in an azimuth direction of rotating on a Z axis of the satellite, and an angle in an elevation direction of rotating on an axis vertical to the angle in the azimuth direction (i.e., an axis in a direction on an X-Y plane of the satellite).
FIG. 1 is a diagram illustrating an orientation of an antenna on three-dimensional (3D) coordinates, in which an azimuth α 110 and an elevation β 120 are indicated with respect to an antenna orientation p 100. When an antenna of a satellite is correctly oriented to a ground station from a certain point in an orbit of the satellite, an orientation of the antenna in a satellite body coordinate system may be calculated using orbit information and attitude information of the satellite and location information of the ground station. Referring to FIG. 1, the azimuth α 110 and the elevation β 120 may be calculated using the 3D coordinates (x, y, z) of the antenna orientation p 100 as represented by Equation 1 below.
                              α          =                                    tan                              -                1                                      ⁡                          (                              y                x                            )                                      ⁢                                  ⁢                  β          =                                    sin                              -                1                                      ⁡                          (              z              )                                                          [                  Equation          ⁢                                          ⁢          1                ]            
Thus, an azimuth and an elevation at which an antenna of a satellite needs to have in an entire section for communication may be calculated in advance, and be uploaded to the satellite to be used.